Boron Cantilever and Ruby Cantilever, Why Ruby?

With respect to Be, its the oxide(s) that are toxic. For years and years the electronics industry commonly used BeCu (Be copper) alloys in connector pins and relay contacts. But, as with lead (solder), our big brother EPA and other regulatory agencies have decided to ban its use for "our own protection".

Boron is a very common environmental element, and its oxides are harmless for the most part (boraxes). If you measure the composition of "dust" particles, you will find boron as one of the major components besides silicon dioxide. So your are breathing these Boron containing particles in whether you realize it or not.

I am amazed they are using sapphire (ruby) or even diamond as a cantalever material. Besides the cost, these are very brittle and fragile materials.

Mechans:

Diamond and sapphire are extremely brittle, in that you cannot bend or flex them without breakage. I did not mean they were not strong materials.

In a long needle shaped (ie length>>>diameter) structure like a cantalever, they would be very fragile. As used in jewelry in bulk crystal form, of course not.

In a cantalever, they are probably attached to an elastomer of some sort to allow flexing and movement. This allows some degree of freedom but I still suggest that these must be handled with the utmost care.